Resumen del producto

Ontogenetic changes in fish larvae are reflected in their assemblages. Because of the differences in each early developmental stage, assemblages will be correlated to different environmental characteristics, or with different intensities, from those observed when we do the traditional analysis which includes all developmental stages in one integrated group. To prove the utility of a segregated analysis, fish larvae assemblages formed off Baja California were analyzed in each developmental stage and in the integrated group of developmental stages. Zooplankton was collected in oblique-tows between 1998 and 2000. From these samples, mayor zooplankton groups were identified and total fish larvae were extracted, identified and segregated by developmental stage as preflexion, flexion and postflexion larvae. In each sampling station CTD casts were made recording sea parameters, and water was sampled to obtain chlorophyll-a concentrations. Bray-Curtis index and Canonic correlation analysis were used to describe the fish larvae assemblages in each developmental stage and to describe the relationship between these and sea parameters. Two kinds of larvae assemblages were formed: those from oceanic species, which correlated better whit physicochemical parameters, and those from coastal-related species, correlated whit both, biological and physicochemical parameters. An ontogenetic segregation was observed in the distribution of the assemblages because of the different environmental requirements of each developmental stage. The preflexion larvae assemblages were correlated mainly with physicochemical parameters and more developed larvae assemblages were also correlated with geographic and biological parameters, even those of oceanic species. We concluded that the analysis of the integrated group of developmental stages shows correlation with several environmental variables, but the segregated analysis of each developmental stage is more specific for the major variables that have an influence in their distribution; therefore this segregated analysis results in better environmental indicators.

Palabras clave: variabilidad climática; Agua Subártica; IMECOCAL

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